They were a race with only one mother and it she was called Mom because she was the origin of all momentum.

Forward: It seems logical if you were going to devise a life form that would be inherently immortal that it would be based on something that is indestructible. This is their structure, they were born of momentum and as such, could not be destroyed without violating the law of conservation of momentum.

As I dreamed it, it has many different aspects and the strangest thing is that they dreamed of me and the one thing I had which they wanted, mortality!